Beamforming architecture for multi-beam multiple-input-multiple-output (mimo)

ABSTRACT

In various aspects, a Multiple-Input-Multiple-Output (MIMO) antenna array configuration, a wireless communication device, and a method for receiving multiple beamformed signals are described herein. According to at least one aspect, a MIMO antenna array configuration is described to include a plurality of Radio Frequency (RF) chains, a plurality of antenna elements, and a plurality of phase shifters. In some aspects, the antenna elements and phase shifters form a plurality of antenna arrays. The number of antenna arrays is, in at least one aspect, larger than the number of RF chains.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a national stage entry of InternationalApplication No. PCT/CN2016/078245 under 35 U.S.C. §§ 365 and 371, filedon Apr. 1, 2016, and is incorporated herein by reference in its entiretyand for all purposes.

FIELD

The present disclosure generally relates to communications architecturefor wireless communications devices, methods, and systems for receivingor transmitting multiple beamformed signals in MIMO wirelesscommunications.

BACKGROUND

Modern wireless communications device may include a plurality ofantennas to support advanced communications technologies. For example,data may be received or transmitted via a plurality of antennas toachieve higher robustness and throughput. A plurality of antennas, forexample, an array of antennas, with phases of signals at each antennashifted by an amount, for example, a phased antenna array, may be usedfor beamforming techniques. Beamforming techniques can improve signalquality at an intended device while reducing unintended interference toor from other directions by controlling directional pattern of antennas.An efficient architecture may be desired for controlling directions oftransmit or receive beams to any desired angles, or to any desiredcombinations of angles, and for supporting full-rank MIMO to, forexample, achieve a large number of spatially multiplexed signal layers.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different view. The drawings are not necessarily toscale, emphasis instead generally being place upon illustrating theprinciples of the present disclosure. In the following description,various aspects are described with reference to the following drawings,in which:

FIG. 1 shows a wireless communications system, for example, a 5^(th)Generation (5G) wireless communications system in accordance with someembodiments.

FIG. 2 shows a baseline single-beam-per-array configuration.

FIG. 3 shows a dual-beam-per-array configuration.

FIGS. 4a and 4b show reception of dual-layer Spatial Multiplexing (SM)signals with a baseline single-beam-per-array configuration and adual-beam-per-array configuration.

FIG. 5 shows a four-sided (rectangle) antenna array configuration inaccordance with some embodiments.

FIG. 6 shows reception of dual-layer Spatial Multiplexing (SM) signalswith a four-sided (rectangle) antenna array configuration in accordancewith some embodiments.

FIG. 7 shows a flow diagram illustrating an example method for selectingand receiving a beamformed signal in accordance with some embodiments.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawingsthat show, by way of illustration, specific details and aspects of thepresent disclosure. Other aspects may be utilized and structural,logical, and electrical changes may be made without departing from thescope of the present disclosure. The various aspects of the presentdisclosure are not necessarily mutually exclusive, as some aspects ofthe present disclosure can be combined with one or more other aspects ofthe present disclosure to form new aspects.

FIG. 1 shows a wireless communications system 100, for example, a 5Gwireless communications system in accordance with some embodiments.

The wireless communications system 100, for example, a 5G wirelesscommunications system, includes a radio access network 101. The radioaccess network 101 may include base stations 120-122. Each base station,for example, the base station 120, may provide radio coverage for one ormore mobile radio cells, for example mobile radio cell 110, of the radioaccess network 101.

A plurality of wireless communications devices 130-132 (also referred toas mobile terminals, User Equipment (UEs), Mobile Stations (MS), ormobile devices) may be located in the mobile radio cell 110 of thewireless communications system 100. A wireless communications device,for example wireless communications device 130, may communicate withother wireless communications devices, for example wirelesscommunications device 131 or 132, via a base station, for example basestation 120, providing coverage for (in other words, operating) themobile radio cell, for example mobile radio cell 110.

For radio communications via an air interface channel, for examplechannel 140, a wireless communications device, for example wirelesscommunications device 130, may include a chain of Radio Frequency (RF)components 151, a plurality of antennas 150, and a baseband processor152. A chain of RF components 151, which may also be referred to as anRF chain, may include an RF receiver, an RF transmitter, or an RFtransceiver. A plurality of antennas 150 can be for example a phasedantenna array. A baseband processor 152 may include, for example, ananalog baseband to provide analog signal processing; anAnalog-to-Digital Converter (ADC) and Digital-to-Analog Converter (DAC)to provide conversions between the analog and digital domains; and adigital baseband to provide digital signal processing.

The wireless communications device, for example wireless communicationsdevice 130, may be within coverage of one or more mobile communicationsnetworks that may operate according to a same RAT (Radio AccessTechnology) or according to different RATs.

The radio access network 101 may support communications according tovarious communications technologies, e.g. mobile communicationsstandards. Each base station, for example 120, may provide a radiocommunication connection via air interface channel, for example airinterface channel 140, between the base station 120 and a wirelesscommunications device, for example wireless communications device 130,according to 5G, LTE (Long Term Evolution), UMTS (Universal MobileCommunications System), GSM (Global System for Mobile Communications),EDGE (Enhanced Data Rates for GSM Evolution) radio access.

A MIMO wireless communications system may be supported via multiplexinga plurality of spatially separable signal layers. Spatial separation ofsignal layers may be achieved with a plurality of beams by mapping oneor more but not all MIMO layers to, for example, one transmit (Tx) beamat a transmitter. This type of spatial multiplexing scheme, hereindenoted as multi-beam MIMO, may be an integral part of a wide range ofcommunications systems including 5G. For example, a receiver may employa plurality of receive (Rx) beams, with directions of the one or more Rxbeams being selected according to a criterion to increase, for example,maximize, received signal quality of one signal from one Tx beam.Bilateral beamforming, in both transmit and receive directions, may beespecially useful in high frequency bands, for example, millimeter wavebands (30-300 GHz), due to high atmospheric attenuation and materialabsorption characteristics of radio waves in the high frequency bands.

A bilateral L-beam (L≥2, with L being an integer) MIMO supporting atleast P·L layers may be achieved by L beams and at least P·L RF chainsat a transmitter or a receiver. P ∈ {1,2}, and denotes a number ofpolarizations that such a bilateral L-beam MIMO supports. For example,if P=1, MIMO supports single-polarized transmission, and if P=2 MIMOsupports cross-polarized transmission. An RF chain herein denotes alogical single-layer RF chain entity. An RF chain may include, forexample, an RF receiver, an RF transmitter, or an RF transceiver. An RFchain may be, for example, a physical RF block that can process multipleparallel layers, for example, both polarization components of across-polarized signal. A number of RF chains is kept to a low number toresolve P·L spatially-multiplexed layers for a L-beam MIMO, for example,P·L RF chains, due to cost, hardware size, and power consumption of anRF chain.

Moreover, a directional antenna, including a phased antenna array, haslimited Field Of View (FOV). An FOV is an angular span to which a mainlobe of an antenna array may be directed. One application of beamformingat wireless communications devices is, for example, to support MIMOcommunications where signals are spatially multiplexed using multiplesimultaneously beamformed signals. For transmitting or receivingbeamformed signals, a beamforming transmitter or beamforming receivermay couple to a directional antenna or a phased antenna array. LimitedFOV of a directional antenna, for example, a phased antenna array, meansthat to direct L beams to any desired angle or any desired combinationsof angles, a beamforming transmitter or receiver may require multiplebeams at each antenna array or at more than L antenna arrays. Comparedto a transmitter, a receiver may have less freedom to choose beamdirections for signals it receives.

An efficient antenna array configuration of phased antenna arrays and RFchains may, for example, reduce costs while providing sufficientbeamforming performance, for example, beamwidth, gain, and ability tosupport any desired combinations of directions. Such configuration maysupport L-beam MIMO.

A bilateral L-beam (L≥2, with L being an integer) MIMO supporting atleast P·L layers may be formed with P·L RF chains and 2L antenna arrays,where P ∈ {1,2}. Each of the RF chains forms may be associated with asingle-polarization signal. Each of the antenna arrays may face adistinct direction, for example, a normal direction, defined asboresight with 0° phase shift, of each of the 2L antenna arrays may bedistinct. For one class of beamforming devices that supports anycombinations of L simultaneous beam directions across a 3-Dimensional(3D) sphere, antenna arrays may be placed in a polyhedron pattern with2L sides, with FOVs of the antenna arrays (sides) facing outward frompolyhedron. For one class of beamforming devices, resolvability of beamdirections on a 2-Dimensional (2D) plane may be more important, andpolyhedron pattern of antenna arrays for such class of beamformingdevices may be reduced to a polygon pattern with 2L sides. For example,if azimuth-elevation orientation of such class of beamforming devices isstable, beam granularity in an elevation plane may be less importantthan that in an azimuthal plane. For transmission, output of an RF chainmay map to only one antenna array. For reception, input to an RF chainmay come from one selected antenna array or may be a combined signalfrom more than one antenna arrays.

Hereafter, for ease of illustration, simplified single-polarizedexamples of 2-Dimensional (2D) dual-beam MIMO scenarios, which support2-layers (4-layers if cross-polarization), are described. A 2D plane of2D examples may be denoted as an azimuthal plane. Furthermore, idealscenarios are introduced, for example, a phased antenna array has 180°FOV, for example, ±90° from a normal direction, whereas maximum FOV inpractice may be less than 180°, for example 120°. This could be due toimpacts of array substrate, reflector, or other objects onelectromagnetic wave fronts of wireless signals. Therefore, exampleembodiments introduced herein may be extended or modified, for example,a phased antenna array supporting more than 2L sides. In someembodiments, combined FOVs of any group of antenna arrays may be coupledto any given RF chains to form coverage of desired beam directions.

FIG. 2 shows a baseline phased antenna array configuration 200 fordual-beam MIMO SM reception. The baseline phased antenna arrayconfiguration 200 may be the simplest configuration for a dual-arraywith single-beam per array. The baseline phased antenna arrayconfiguration 200 may hereinafter also be referred to as a baselineconfiguration 200. In an ideal 2D scenario of 180° FOVs, the baselineconfiguration 200 may provide complete 360° coverage. The baselineconfiguration may employ RF chains 210 and 250. The baselineconfiguration 200 may also employ phase shifters 211-218 and antennaelements 231-238 connected to one RF chain 210, and phase shifters251-258 and antenna elements 271-278 connected to the other RF chain250. The phase shifters and antenna elements may form a plurality ofantenna arrays with an FOV boundary 201. As described, there are 2 RFchains, 16 antenna elements, and 16 phase shifters in the examplebaseline configuration 200.

A 3-Dimensional (3D) extension of the baseline configuration 200 may beconstructed by stacking additional rows of antenna elements in anelevation plane. This may provide not only azimuthal beam granularitybut also elevation beam granularity, for example, 3D beamformingcoverage. Such a 3D configuration may be taken as a baseline model, forexample, in 5G industry for developing beamforming framework for UEs.

FIG. 3 shows a multi-beam-per-array configuration 300 for dual-beam MIMOSM reception. The multi-beam-per array configuration 300, which may alsobe referred to as a mesh configuration 300, may employ RF chains, forexample RF chains 310 and 350. The mesh configuration 300 may alsoemploy phase shifters 311-318 and 321-328 and antenna elements 331-338connected to one RF chain 310, and phase shifters 351-358 and 361-368and antenna elements 371-378 connected to the other RF chain 350. Thephase shifters and antenna elements form a plurality of antenna arrayswith an FOV boundary 301. Compared to the baseline configuration 200illustrated by FIG. 2, the mesh configuration 300 may utilize twice asmany phase shifters and also additional hardware, for example, signalsplitters, signal combiners, power amplifiers, and low noise poweramplifiers. As described, there may be 2 RF chains, 16 antenna elements,32 phase shifters, 16 signal splitters, 16 signal combiners, 16 poweramplifiers, and 16 low noise amplifiers in the example meshconfiguration 300. In addition, the mesh configuration 300 may includeadditional hardware to combat side-effects, for example, the meshconfiguration 300 may utilize dedicated signal processing in RF chainsand in baseband to handle intermodulation distortion of nonlinear activedevices such as power amplifiers.

FIGS. 4a and 4b show a dual-layer MIMO SM scenario where two or morebeamformed signals arrive at FOV of only one of the antenna arrays inaccordance with some embodiments. FIG. 4a shows, for example, adual-layer MIMO SM scenario 400 where two or more beamformed signalsarrive at an FOV of only one of the antenna arrays of a baselineconfiguration 200. If, for example, two transmit signals carried by Txbeams 280 and 281 arrive at an FOV of one of the antenna arrays, forexample, antenna array 1 coupled to RF chain 210, only one signal, forexample the transmit signal carried by Tx beam 280 can be received viaRx beam 290. The baseline configuration may not support the intendedfull-rank (2-layer) 2-beam MIMO, and instead may need to fallback to1-layer transmission with reduced throughput in such a scenario. FIG. 4bshows a mesh configuration, for example, a dual-layer MIMO SM scenario410 where two or more beamformed signals arrive at an FOV of only one ofthe antenna arrays of a dual-beam-per-array mesh configuration 300. If,for example, two transmit signals carried by Tx beams 380 and 381 arriveat an FOV of one of the antenna arrays, for example, antenna array 1coupled to RF chain 310 and RF chain 350, two signals, for example, thetwo transmit signals carried by Tx beams 380 and 381 can be received viaRx beams 390 and 391. Compared to the baseline configuration 200, themesh configuration 300 may support such scenario, for example, two ormore beamformed signals arrive at an FOV of only one of the antennaarrays.

As shown, the baseline configuration 200 illustrated by FIG. 2 may havea limitation in achieving maximum data throughput. It, for example, maynot receive or resolve dual-layer SM signals carried by two Tx beams ifboth of them arrive at an FOV of one antenna array, for example, theantenna array coupled to RF chain 210, which may be in a blind zone ofthe other antenna array, for example, the antenna array coupled to RFchain 250. In general, the baseline configuration 200 may not receivemulti-beam MIMO signals if signals carried by two or more Tx beamsarrive at an FOV of only one antenna array. The mesh configuration 300illustrated by FIG. 3 can form two main lobes per antenna array toreceive and resolve dual-layer SM signals carried by two Tx beamsarriving at any angle and, therefore, may achieve increased throughput.However, implementation effort and cost of use may be high.

In the following, a phased antenna array for high performance and highefficiency is described. FIG. 5 shows a single-polarized polyhedronantenna array configuration 500, for example a polygon antenna arrayconfiguration in 2D in accordance with some embodiments. Thesingle-polarized polyhedron antenna array configuration 500, which mayalso be referred to as antenna array configuration 500, may employ anumber of antenna elements and phase shifters that form a plurality ofantenna arrays, for example, antenna arrays 505, 506, 507, and 508 witha vertical FOV boundary 501 and a horizontal FOV boundary 502. Theantenna array configuration 500 may employ RF chains, for example, RFchains 510 and 550, coupled to the number of antenna elements and phaseshifters, for example, coupled to a plurality of antenna arrays. The FOVboundary 501 and the FOV boundary 502 are, for example, perpendicular toeach other. The FOV boundary 501 and the FOV boundary 502 may also beconfigured in other positions relative to each other. For example, theFOV boundary 501 can be positioned at any angle to the FOV boundary 502.Furthermore, the FOV boundary 501 and the FOV boundary 502 can bepositioned at any angle with respect to a wireless communicationsdevice.

On a vertical level, one RF chain, for example, RF chain 510 may have asymmetric arrangement of phase shifters and antenna elements on bothsides of the FOV boundary 501. For example, antenna array 505, which mayinclude four phase shifters 511-514 and four antenna elements 531-534,may be connected to the RF chain 510, from a first side of the FOVboundary 501, and antenna array 507, which may include another fourphase shifters 515-518 and another four antenna elements 535-538, may beconnected to the RF chain 510 from a second side of the FOV boundary501. The antenna arrays 505 and 507 may be considered symmetrical withone another as they are coupled with a common RF chain from opposingsides. On a horizontal level, the other RF chain, for example, RF chain550, may have a symmetric arrangement of phase shifters and antennaelements on both sides of FOV boundary 502. For example, antenna array508, which may include four phase shifters 551-554 and four antennaelements 571-574, may be connected to the RF chain 550 from a first sideof the FOV boundary 502, and antenna array 506, which may includeanother four phase shifters 555-558 and another four antenna elements575-578, may be connected to the RF chain 550 from a second side of theFOV boundary 502. The antenna array 506 may be symmetrical with antennaarray 508. Asymmetric arrangements may be also made to constructfour-sided antenna array configurations or other polygon arrayconfigurations.

In a 2D configuration, such as antenna array configuration 500, four(2L, L=2) single-beam antenna arrays may be formed, for example, witheach RF chain being coupled to two antenna arrays. As shown, any pair ofdistinct Rx beams can be simultaneously supported by two antenna arraysthat are associated with two RF chains, respectively. For example, on avertical level, antenna array 505 may have a FOV with a range from 270°to 90° and antenna array 507 may have a FOV with a range from 90° to270°. For example, on a horizontal level, the antenna array 506 may havea FOV with a range from 0° to 180°, and the antenna array 508 may have aFOV with a range from 180° to 0°. As described, a four-sided antennaarray configuration, for example, a rectangle array configuration, isformed. Other polygon array configurations in 2D may be also formed.Furthermore, in various embodiments, a number of antenna elements andphase shifters form a plurality of antenna arrays. The number of antennaelements and phase shifters that form each of the plurality of antennaarrays, for example, antenna arrays 505, 506, 507, and 508, may bedifferent.

A four-sided antenna array configuration may exhibit a number ofprinciples. For a first example, for each polarization, a four-sidedantenna array configuration may include more antenna arrays than RFchains. For a second example, an FOV of each antenna array may cover adistinct range of directions for transmission and reception of signals,and a distinct range of directions supported by each antenna array maypartially overlap. For a third example, neighboring antenna arrays maybe coupled to different RF chains. Furthermore, combined FOVs of allantenna arrays coupled to any given single RF chain may form completecoverage of desired beam directions, e.g., a complete 360°. Adhering tothe principles, the example four-sided antenna array configuration maybe extended to non-symmetric four-sided antenna array configurations orother polygon configurations with more antenna arrays (sides), forexample hexagon (six-sided) configurations supporting 3 beams or octagon(eight-sided) configurations supporting 4 beams.

An example asymmetric four-sided antenna array configuration may includea plurality of antenna arrays with each of the antenna arrays includinga different number of antenna elements and phase shifters. For example,a first antenna array may include three antenna elements and phaseshifters, a second antenna array may include four antenna elements andphase shifters, a third antenna array may include five antenna elementsand phase shifters, and a fourth antenna array may include six antennaelements and phase shifters.

Another example asymmetric four-sided antenna array configuration mayinclude antenna arrays coupled with a common RF chain including adifferent number of antenna elements and phase shifters. For example, afirst antenna array may include three antenna elements and phaseshifters and a second antenna array, coupled to the same RF chain as thefirst antenna array, may include four antenna elements and phaseshifters. In various embodiments, the first and second antenna arraysmay include the same or different numbers of antenna elements and phaseshifters as third and fourth antenna arrays. For example, with respectto the antenna array configuration 500, antenna array 505 may have adifferent number of antenna elements and phase shifters than antennaarray 507, but may include the same (or a different) number of antennaelements and phase shifters as antenna array 506, or antenna array 508.

In some embodiments, an asymmetric four-sided antenna arrayconfiguration may include a plurality of antenna arrays with each of theplurality of antenna arrays having a normal direction that is distinctfrom normal directions of the other antenna arrays.

In some embodiments, an asymmetric four-sided antenna arrayconfiguration may include a plurality of antenna arrays with each of theantenna arrays having a different FOV.

In some embodiments, a hexagon (six-sided) antenna array configurationcan support 3 beams. A hexagon configuration can be symmetric orasymmetric.

In some embodiments, an octagon (eight-sided) antenna arrayconfiguration can support 4 beams. An octagon configuration can besymmetric or asymmetric.

In various embodiments, 3D polyhedron antenna array configurations maybe constructed. Normal directions of member antenna arrays of a 3Dpolyhedron antenna array configuration may address all three axes of 3Dspace. For example, for a 3-beam MIMO, six antenna arrays coupled tothree RF chains may form a hexahedron. This may reduce to a cube in asymmetric subcase. In general, a 2L-sided polyhedron antenna arrayconfiguration can be constructed for L-beam MIMO with P·L RF chains and2L antenna arrays.

Such a four-sided antenna array configuration may support anysimultaneous pair of distinct Rx beam directions compared to thebaseline configuration illustrated by FIG. 2. Moreover, for such afour-sided antenna array configuration, no additional hardwarecomponents, for example phase shifters, signal splitters, signalcombiners, power amplifiers, or low noise amplifiers are requiredcompared to the mesh configuration illustrated by FIG. 3.

FIG. 6 shows reception of spatially multiplexed dual-layer signals witha four-sided (rectangle) antenna array configuration 600 in accordancewith some embodiments. If, for example, two transmit signals carried bytwo Tx beams, for example, Tx beams 580 and 581, arrive at FOV of anyone of the antenna arrays 505-508 coupled to RF chains 510 and 550, theycan be received via two Rx beams, for example, Rx beams 590 and 591.Compared to the baseline configuration 200 or the mesh configuration 300illustrated by FIGS. 2 and 3, respectively, the four-sided antenna arrayconfiguration can support the scenarios where two or more beamformedsignals arrive at FOV of any one of the antenna arrays. This is becauseneighboring antenna arrays have overlapping FOVs and are coupled todifferent RF chains.

For example, two transmit signals carried by Tx beams 580 and 581 mayarrive at different angles to FOV boundary 502. One transmit signalcarried by Tx beam 580, for example, may arrive at an angle of 45° toFOV boundary 502, and the other transmit signal carried by Tx beam 581,for example, may arrive at an angle of 60° to FOV boundary 502. In thisscenario, one transmit signal can be received via Rx beam 590 by antennaarray 505 coupled to RF chain 510, and the other transmit signal can bereceived via Rx beam 591 by antenna array 506 coupled to RF chain 550.

For example, two transmit signals carried by Tx beams 580 and 581 mayarrive at different angles to FOV boundary 502. One transmit signalcarried by Tx beam 580, for example, may arrive at an angle of 30° toFOV boundary 502, and the other transmit signal carried by Tx beam 581,for example, may arrive at an angle of 210° to FOV boundary 502. In thisscenario, one transmit signal can be received via Rx beam 590 by antennaarray 505 coupled to RF chain 510, and the other transmit signal can bereceived via Rx beam 591 by antenna array 508 coupled to RF chain 550.Or, one transmit signal can be received via Rx beam 590 by antenna array506 coupled to RF chain 550, and the other transmit signal can bereceived via Rx beam 591 by antenna array 507 coupled to RF chain 510.Other reception arrangements can also be made.

As such, the four-sided antenna array configuration can receive andresolve two or more beamformed signals arriving at any angles. Suchconfiguration may achieve an increased throughput of multi-beam MIMO.

The class of polyhedron antenna array configurations, including anexample four-sided antenna array configuration illustrated by FIG. 5,may be used for efficient transmission of multi-beam MIMO signals inaddition to reception as shown in above examples. Moreover, theconfigurations allow directing two or more transmit beams, each carryinga distinct signal from an RF chain, in any combinations of angles. Incontrast, a baseline configuration cannot direct its Tx beams to anycombinations of angles. A mesh configuration can direct its Tx beams toany combinations of angles, however, at a cost of signal combiners,power amplifiers, and extra phase shifters.

Components of the wireless communications device, for example,transmitter, receiver, phase shifters, antenna elements, signalsplitters, signal combiners, power amplifiers, low noise amplifiers mayfor example be implemented by one or more circuits. A “circuit” may beunderstood as any kind of a logic implementing entity, which may bespecial purpose circuitry or processor executing software stored in amemory, firmware, or any combination thereof. Thus a “circuit” may be ahard-wired logic circuit or a programmable logic circuit such as aprogrammable processor, e.g. a microprocessor. A “circuit” may also be aprocessor executing software, e.g. any kind of computer program. Anyother kind of implementation of the respective functions which will bedescribed in more detail below may also be understood as a “circuit”.

A wireless communications device is embedded with, for example, a2L-sided polyhedron antenna array configuration with L RF chains, whichsupport L-Layer multi-beam MIMO. The 2L-sided polyhedron antenna arrayconfiguration, for example when L=2, can be a 4-sided arrayconfiguration illustrated by FIG. 5 which carries out an example methodfor receiving or transmitting beamformed signals as illustrated by FIG.7. As described, the wireless communications device can be a UE, amobile device, a receiver, a transmitter, or a MS.

FIG. 7 shows a flow diagram 700 that illustrates a flow diagramdepicting an example method for selecting Rx beams and receivingbeamformed signals in accordance with some embodiments.

In 710, a wireless communications device embedded with a polyhedronantenna array configuration, for example a four-sided antenna arrayconfiguration illustrated by FIG. 5, receives, for example, a referencesignal. The wireless communications device may receive a referencesignal from base stations, for example base station 120 illustrated byFIG. 1. A reference signal, also known as a pilot, denotes a group ofdistinct time-frequency resources occupied by pre-determined signals ofknown pattern. There may be one or more reference signals. The wirelesscommunications device makes multiple independent observations of thereference signal with an Rx beam among an associated number of candidateRx beam directions supported by each antenna array. For example, duringeach independent observation, it observes the reference signal using onecandidate Rx beam supported by each antenna array at a time. With suchindependent observations, each antenna array cycles through candidate Rxbeams it supports. Moreover, multiple independent observations can bemade at each antenna array in parallel.

In 720, the wireless communications device embedded with a four-sidedantenna array configuration illustrated by FIG. 5 has for example aselection criterion. There may be one or more selection criteria. Foreach RF chain, for example RF chain 510 or 550, the wirelesscommunications device selects at most one Rx beam out of the associatednumber of candidate Rx beam directions supported by each antenna arrayaccording to the selection criterion. Moreover, one Rx beam out of eachantenna array can be selected in parallel. The selected Rx beamrepresents for example high signal strength, high Signal-to-Noise Ratio(SNR). As described, the selected Rx beam contributes to good signalreception or transmission.

In 730, the selected L Rx beams are used for signal reception until anext beam training cycle starts, i.e. each antenna array observing areference signal with each candidate Rx beam among an associated numberof candidate Rx beam directions supported by each antenna array, each RFchain selecting one Rx beam out of the candidate Rx beams among theassociated number of candidate Rx beam directions according to theselection criterion. In 730, the selected Rx beams, for example in 720are used at the antenna arrays to capture target signals. The targetsignals are amplified and down converted to baseband, digitized at abank of ADC, and MIMO decoded (demultiplexed) to reproduce transmitteddata.

For signal transmission, it follows a similar beam training cycleprocess. If there is Tx-Rx channel reciprocity, a transmit beam may bethe same as a selected receive beam. Moreover, a L-beam MIMO signaltransmission with a polyhedron antenna array configuration may forexample include modulating L individually identifiable referencesignals, sending each reference signal to one RF chain, transmittingeach reference signal by using one Tx beam at one antenna array coupledto the associated RF chain. The L reference signals may besimultaneously transmitted. Tx beams may be cycled for each RF chain.Based on Tx-beam-cycled reference signals, base stations, for examplebase station 120 illustrated by FIG. 1, may feedback identifiers onwhich Tx beam for each RF chain works the best. A UE then transmit datasignals using the identified set of Tx beams.

The following examples pertain to further embodiments.

Example 1 is a Multiple-Input-Multiple-Output (MIMO) antenna arrayconfiguration illustrated by FIG. 5.

In Example 2, the subject matter of Example 1 may optionally includeeach neighboring antenna array of the plurality of antenna arrays beingcoupled to a different RF chain of the plurality of RF chains.

In Example 3, the subject matter of any of Examples 1-2 may optionallyinclude each antenna array of the plurality of antenna arrays covering adistinct range of directions for transmission and reception of signals,and distinct ranges of directions supported by the plurality of antennaarrays partially overlapping.

In Example 4, the subject matter of any one of Examples 1-3 mayoptionally include a same number of the plurality of antenna elementsand phase shifters forming each of the plurality of antenna arrays.

In Example 5, the subject matter of any one of Examples 1-3 mayoptionally include a different number of the plurality of antennaelements and phase shifters forming each of the plurality of antennaarrays.

In Example 6, the subject matter of any one of Examples 1-3 mayoptionally include a number of the plurality of antenna elements andphase shifters that form a first antenna array being the same as anumber of the plurality of antenna elements and phase shifters that forma second antenna array that is symmetric with the first antenna array.

In Example 7, the subject matter of any one of Examples 1-3 mayoptionally include a number of the plurality of antenna elements andphase shifters that form a first antenna array being different from anumber of the plurality of antenna elements and phase shifters that forma second antenna array that is symmetric with the first antenna array.

In Example 8, the subject matter of any one of Examples 1-3 mayoptionally include a number of the plurality of antenna elements andphase shifters that form a first antenna array being the same as anumber of the plurality of antenna elements and phase shifters that forma second antenna array that is asymmetric with the first antenna array.

In Example 9, the subject matter of any one of Examples 1-3 mayoptionally include a number of the plurality of antenna elements andphase shifters that form a first antenna array being different than anumber of the plurality of antenna elements and phase shifters that forma second antenna array that is asymmetric with the first antenna array.

In Example 10, the subject matter of any one of Examples 1-9 mayoptionally include the MIMO antenna array configuration supportingfull-rank MIMO.

Example 11 is a wireless communications device. The wirelesscommunications device may optionally include a plurality of antennaarrays configured for a Multiple-Input-Multiple-Output (MIMO) antennaarray configuration, a receiver coupled to the MIMO antenna arrayconfiguration to receive signals, and a transmitter coupled to the MIMOantenna array configuration to transmit signals. The MIMO antenna arrayconfiguration may optionally include a plurality of Radio Frequency (RF)chains coupled to the plurality of antenna arrays, and the number ofantenna arrays may be optionally larger than the number of RF chains.

In Example 12, the subject matter of Example 11 may optionally includeneighboring antenna array of the plurality of antenna arrays beingcoupled to a different RF chain of the plurality of RF chains.

In Example 13, the subject matter of any one of Examples 11-12 mayoptionally include each antenna array of the plurality of antenna arrayscovering a distinct range of directions for transmission and receptionof signals, and distinct ranges of directions supported by the pluralityof antenna arrays partially overlapping.

In Example 14, the subject matter of any one of Examples 11-13 mayoptionally include the receiver receiving the signals carried by receivebeams via the MIMO antenna array configuration.

In Example 15, the subject matter of any one of Examples 11-14 mayoptionally include the transmitter transmitting the signals carried bytransmit beams via the MIMO antenna array configuration.

In Example 16, the subject matter of any one of Examples 11-15 mayoptionally include each of the plurality of antenna arrays including asame number of antenna elements and phase shifters.

In Example 17, the subject matter of any one of Examples 11-15 mayoptionally include each of the plurality of antenna arrays including adifferent number of antenna elements and phase shifters.

In Example 18, the subject matter of any one of Examples 11-15 mayoptionally include individual antenna arrays of the plurality of antennaarrays including a plurality of antenna elements and phase shifters, anda number of the plurality of antenna elements and phase shifters for afirst antenna array of the plurality of antenna arrays being the same asa number of the plurality of antenna elements and phase shifters for asecond antenna array of the plurality of antenna arrays that issymmetric with the first antenna array.

In Example 19, the subject matter of any one of Examples 11-15 mayoptionally include individual antenna arrays of the plurality of antennaarrays including a plurality of antenna elements and phase shifters, anda number of the plurality of antenna elements and phase shifters for afirst antenna array of the plurality of antenna arrays being differentfrom a number of the plurality of antenna elements and phase shiftersfor a second antenna array of the plurality of antenna arrays that issymmetric with the first antenna array.

In Example 20, the subject matter of any one of Examples 11-15 mayoptionally include individual antenna arrays of the plurality of antennaarrays including a plurality of antenna elements and phase shifters, anda number of the plurality of antenna elements and phase shifters for afirst antenna array of the plurality of antenna arrays being the same asa number of the plurality of antenna elements and phase shifters for asecond antenna array of the plurality of antenna arrays that isasymmetric with the first antenna array.

In Example 21, the subject matter of any one of Examples 11-15 mayoptionally include individual antenna arrays of the plurality of antennaarrays including a plurality of antenna elements and phase shifters, anda number of the plurality of antenna elements and phase shifters for afirst antenna array of the plurality of antenna arrays being differentfrom a number of the plurality of antenna elements and phase shiftersfor a second antenna array of the plurality of antenna array that isasymmetric with the first antenna array.

Example 22 is a method for receiving multiple beamformed signalsillustrated by FIG. 7.

In Example 23, the subject matter of Example 22 may optionally includethe candidate receive beams being among an associated number ofcandidate receive beam directions of each of the plurality of antennaarrays.

In Example 24, the subject matter of any one of Examples 22-23 mayoptionally include the multiple independent observations being made ateach of the plurality of antenna arrays in parallel.

In Example 25, the subject matter of any one of Examples 22-24 mayoptionally include the receive beam out of each of the plurality ofantenna arrays being selected in parallel.

In Example 26, the subject matter of any one of Examples 22-25 mayoptionally include the selected receive beam representing high signalstrength.

In Example 27, the subject matter of any one of Examples 22-26 mayoptionally include the selected receive beam representing highSignal-to-Noise Ratio (SNR).

In Example 28, the subject matter of any one of Examples 22-27 mayoptionally include the selected receive beam at each of the plurality ofantenna arrays being used for signal reception until a next beamtraining cycle starts.

In Example 29, the subject matter of any one of Examples 22-28 mayoptionally include the selected receive beam at each of the plurality ofantenna arrays being used to capture a target signal.

In Example 30, the subject matter of Example 29 may optionally includethe target signal being amplified and down converted for basebandprocessing to reproduce transmitted data.

In Example 31, the subject matter of any one of Examples 22-30 mayoptionally include the reference signal being a group of distincttime-frequency resources occupied by pre-determined signals of knownpattern.

In Example 32, the subject matter of any one of Examples 22-31 mayoptionally include the selection criterion being one of a group ofselection criteria.

Example 33 is a computer readable medium having recorded instructionsthereon which, when executed by a processor, make the processor performa method for receiving multiple beamformed signals according to any oneof Examples 22 to 32.

It should be noted that one or more of the features of any of theexamples above may be combined with any one of the other examples.

While specific aspects have been described, it should be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of the aspectsof the present disclosure. All changes which come within the meaning andrange of equivalency of the claims are therefore intended to beembraced.

These processes are illustrated as a collection of blocks in a logicalflow graph, which represents a sequence of operations that may beimplemented in mechanics alone or a combination with hardware, software,and/or firmware. In the context of software/firmware, the blocksrepresent instructions stored on one or more computer-readable storagemedia that, when executed by one or more processors, perform the recitedoperations.

The term “computer-readable media” includes computer-storage media. Inone embodiment, computer-readable media is non-transitory. For example,computer-storage media may include, but are not limited to, magneticstorage devices (e.g., hard disk, floppy disk, and magnetic strips),optical disks (e.g., compact disk (CD) and digital versatile disk(DVD)), smart cards, flash memory devices (e.g., thumb drive, stick, keydrive, and SD cards), and volatile and non-volatile memory (e.g., randomaccess memory (RAM), read-only memory (ROM)).

1. A Multiple-Input-Multiple-Output (MIMO) antenna array configuration,comprising: a plurality of Radio Frequency (RF) chains; a plurality ofantenna elements; and a plurality of phase shifters, wherein theplurality of antenna elements and plurality of phase shifters form aplurality of antenna arrays that are coupled to the RF chains, wherein anumber of antenna arrays in the plurality of antenna arrays is largerthan a number of RF chains in the plurality of RF chains.
 2. The MIMOantenna array configuration of claim 1, wherein each neighboring antennaarray of the plurality of antenna arrays is coupled to a different RFchain of the plurality of RF chains.
 3. The MIMO antenna arrayconfiguration of claim 1, wherein each antenna array of the plurality ofantenna arrays covers a distinct range of directions for transmissionand reception of signals, and distinct ranges of directions supported bythe plurality of antenna arrays partially overlap.
 4. The MIMO antennaarray configuration of claim 1, wherein a same number of the pluralityof antenna elements and phase shifters fonn each antenna array, of theplurality of antenna arrays.
 5. The MIMO antenna array configuration ofclaim 1, wherein a different number of the plurality of antenna elementsand phase shifters form each antenna array of the plurality of antennaarrays.
 6. The MIMO antenna array configuration of claim 1, wherein anumber of the plurality of antenna elements and phase shifters that forma first antenna array is the same as a number of the plurality ofantenna elements and phase shifters that form a second antenna arraythat is symmetric with the first antenna array.
 7. The MIMO antennaarray configuration of claim 1, wherein a number of the plurality ofantenna elements and phase shifters that form a first antenna array isdifferent from a number of the plurality of antenna elements and phaseshifters that form a second antenna array that is symmetric with thefirst antenna array.
 8. The MIMO antenna array configuration of claim 1,wherein a number of the plurality of antenna elements and phase shiftersthat form a first antenna array is the same as a number of the pluralityof antenna elements and phase shifters that form a second antenna arraythat is asymmetric with the first antenna array.
 9. The MIMO antennaarray configuration of claim 1, wherein a number of the plurality ofantenna elements and phase shifters that form a first antenna array isdifferent than a number of the plurality of antenna elements and phaseshifters that form a second antenna array that is asymmetric with thefirst antenna array.
 10. The MIMO antenna array configuration of claim1, wherein the MIMO antenna array configuration supports full-rank MIMO.11. A wireless communications device, comprising: a plurality of antennaarrays configured for a Multiple-Input-Multiple-Output (MIMO) antennaarray configuration; a receiver coupled to the MIMO antenna arrayconfiguration to receive signals; and a transmitter coupled the MIMOantenna array configuration to transmit signals, wherein the MIMOantenna array configuration comprises a plurality of Radio Frequency(RF) chains coupled to the plurality of antenna arrays, wherein thenumber of antenna arrays is larger than the number of RF chains.
 12. Thewireless communications device of claim 11, wherein each neighboringantenna array of the plurality of antenna arrays is coupled to adifferent RF chain of the plurality of RF chains.
 13. The wirelesscommunications device of claim 11, wherein each antenna array of theplurality of antenna arrays covers a distinct range of directions fortransmission and reception of signals, and distinct ranges of directionssupported by the plurality of antenna arrays partially overlap.
 14. Thewireless communications device of claim 11, wherein the receiverreceives the signals carried by receive beams via the MIMO antenna arrayconfiguration.
 15. The wireless communications device of claim 11,wherein the transmitter transmits the signals carried by transmit beamsvia the MIMO antenna array configuration.
 16. (canceled)
 17. (canceled)18. A method for receiving multiple beamformed signals, the methodcomprising: making multiple independent observations of a referencesignal through candidate receive beams of each antenna array of aplurality of antenna arrays; and selecting at most one receive beam outof the candidate receive beams of each antenna array of the plurality ofantenna arrays according to a selection criterion.
 19. The method forreceiving multiple beamformed signals of claim 18, wherein the candidatereceive beams are among an associated number of candidate receive beamdirections of each antenna array of the plurality of antenna arrays. 20.The method for receiving multiple beamformed signals of claim 18,wherein the multiple independent observations are made at each antennaarray of the plurality of antenna arrays in parallel.
 21. The method forreceiving multiple beamformed signals of claim 18, wherein the receivebeam out of each antenna array of the plurality of antenna arrays isselected in parallel.
 22. The method for receiving multiple beamformedsignals of claim 18, wherein the selected receive beam represents highsignal strength.
 23. (canceled)
 24. (canceled)
 25. (canceled)